fix(amplify-provider-awscloudformation): add if/else for warning message in sandbox mode

[danielleadams]

Description of changes

Adds the sandbox mode warning to an if/else statement.

• If the sandbox mode is enabled in the GraphQL schema AND the user has an API Key configured, the sandbox mode warning message is displayed on amplify api gql-compile.
• Otherwise, the CLI will recommend adding auth to models if it is missing on any types.

Description of how you validated changes

Tested locally with amplify-dev local binary.

Checklist

• PR description included
• yarn test passes
• Tests are changed or added
• Relevant documentation is changed or added (and PR referenced)
• New AWS SDK calls or CloudFormation actions have been added to relevant test and service IAM policies

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

Merging #8545 (2e1e54e) into master (bd435e2) will increase coverage by 1.22%.
The diff coverage is 75.46%.

@@            Coverage Diff             @@
##           master    #8545      +/-   ##
==========================================
+ Coverage   55.92%   57.14%   +1.22%     
==========================================
  Files         695      724      +29     
  Lines       38881    40849    +1968     
  Branches     7871     8364     +493     
==========================================
+ Hits        21743    23343    +1600     
- Misses      16343    16696     +353     
- Partials      795      810      +15     

Impacted Files	Coverage Δ
...egory-api/src/provider-utils/supported-services.ts	100.00% <ø> (ø)
packages/amplify-category-auth/src/index.js	15.74% <0.00%> (ø)
...auth/src/provider-utils/awscloudformation/index.js	3.90% <0.00%> (ø)
...s/amplify-category-geo/src/commands/geo/console.ts	53.84% <0.00%> (+3.84%)	⬆️
...amplify-cli-core/src/feature-flags/featureFlags.ts	83.62% <ø> (ø)
packages/amplify-cli/src/domain/amplify-toolkit.ts	2.39% <0.00%> (+<0.01%)	⬆️
...index-transformer/src/graphql-index-transformer.ts	100.00% <ø> (ø)
...amplify-graphql-index-transformer/src/resolvers.ts	99.57% <ø> (+<0.01%)	⬆️
...es/amplify-graphql-index-transformer/src/schema.ts	98.19% <ø> (+0.05%)	⬆️
...transformer/src/graphql-predictions-transformer.ts	97.80% <ø> (-1.62%)	⬇️
... and 86 more

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